This invention relates to intrusion detection systems which are used to detect entry into rooms, buildings, or controlled areas, and more particularly to an intrusion detection system which includes a fiber optic acoustic transducer.
Presently, there are a number of intrusion detection systems which are employed to detect the presence of an intruder within a predetermined area to be protected. Usually the detection of an unwanted intrusion will cause activation of a visual and/or audible alarm, either locally in the protected area or at a remote monitoring station.
In general, existing intrusion detection systems depend upon the interruption of an electric current or light beam, or the disturbance of an acoustic or electromagnetic field. These systems radiate energy (current, light, acoustic or electromagnetic) which is detectable by an intruder (either visually or with some type of detection means) and which identifies the type of system and the location of the operative elements to the intruder. Upon detection, the intruder is often able to disable or avoid the detection system, thereby rendering the detection system incapable of detecting the presence or activities of the intruder.
Thus, there is a need in the art for an intrusion detection system which is totally passive and therefore incapable of detection by an intruder. There is a further need for an intrusion detection system employing a transducer which has uniform sensitivity throughout the area to be protected.